High values were obtained for the charge carrier
concentration and DC conductivity of the PEDOT: PSS film from Hall effect and conductivity measurements, respectively, which further confirm that PEDOT:PSS is a metal at room temperature.
When considering the mechanisms of charge transfer, it is shown that as the charge carriers
move into a pore, a metallic type of conductivity is realized.
The nanotextured electrode provides larger surface area in contact with the active materials and helps shortening the travelling distance of the charge carriers
to the corresponding electrodes, hence improving the charge collection and significant improvement of photovoltaic performance.
The authors  refined the bimolecular recombination model in order to account for the charge carrier
density gradients that occur generally in BHJ amorphous organic semiconductor devices.
This is attributed to the space charge polarization that occurs at low frequencies and the motion of electronic charge carriers
. The increasing of the conductivity is small at high frequencies; this is attributed to the electronic polarization and the electronic charge carriers
which travel by hopping process.
In summary [D.sub.id] [right arrow] D [right arrow] [D.sup.*] [right arrow] [D.sup.eff] are the possible diffusion coefficients of each charge carrier
concerned in : Did is that in an ideal defect free lattice, D that in a lattice with point defects only, [D.sup.*] in the given lattice with an applied electric potential, [D.sup.eff] in a real lattice with dislocations under an applied electric potential.
Now, because of the existence of the non-depletion region where high charge carrier
density is residual, the maximum absorption is limited.
In a semiconducting polymer for a transistor, the charge carrier
mobility needs to be high, which requires highly crystalline, highly ordered, highly oriented polymers."
The numerical calculation of [V.sub.s] (k) at different values of the Debye length of screening [L.sub.d], the length of the diffusion of the minority carriers of charge (electron defects) [L.sub.p], the velocity of a surface recombination S, the adhesion coefficient of holes [alpha]p and electrons an has shown that a [V.sub.s] decrease with a k rise in the short-wave region of the spectrum should be observed at [L.sub.p] < [L.sub.d], S [much greater than] 1 and at small values of the adhesion coefficient of both types of charge carriers
on a surface [alpha]p, [alpha]n [approximately equal to] 0  or at [alpha]p [much greater than] 1 and S [much greater than] 1 .
Therefore, the impedance curve includes a short straight line in the low-frequency region, which is caused by the diffusion of ions or charge carriers
at the interface (Fig.
The A.C electrical conductivity is increased with the increasing of concentration of the magnesium oxide nanoparticles, this is related to the hopping of charge carrier
conduction mechanism , as shown in Fig.14.
In the case of the charge carrier
being the proton, the maximum conductivity is reached when the length, [l.sub.0], becomes equal to the reduced Compton wavelength of it, namely